Telephone-exchange system



1 Au 10 I926. 11,595,224

E. E. CLEMENT TELEPHONE EXCHANGE SYSTEM Filed Dec. 9', 1905 s Sheets-Sheet 1 195 Mm; as

Suwantoz Aug. 10 1926. 1,595,224

E. E. CLEMENT TELEPHONE EXCHANGE SYSTEM Filed Dec. 9, 1905 5 Sheets-Sheet 2 awentoo Aug. 10

5' sheets shaet 5 Filed Dec. 9, 1905 RF T Q uoentoz 4 v l H A v g L 7 @v Q Aug. 10

Filed Dec. 9

, 1905 5 Sheets-Sheet. 4

awentoz Aug. 10 1926.

E. E. CLEMENT TELEPHONE EXCHANGE SYSTEM Filed Dec 9, 1905 5 Sheets-Sheet 5 1 9: We: a

Patented Aug. 10, 1926.

UNITED STATES PATENT orrlcs.

EDWARD E. CLEMENT, WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE NORTH ELECTRIC MANUFACTURING COMPANY.

TELEPHONE-EXCHAN GE SYSTEM.

Application flied December 9, 1305. Serial 1T0. 291,097.

My invention relates .to telephone exchange systems, and has for its object the production of a system wherein no' operators shall be required to eifect intercon- 5 nection between subscribers lines, each subscriber having means under his own control automatically to efiect connection and disconnection. The system I' shall hereinafter describe may be called a full auto matic system, because the entire operation from start to finish is controlled through central-oflice machines by subscribers.

The 'main distinguishing feature of the invention consists in the operation of automatic switches by means of certain relays located at the central station, the latter be-" ing designed" to respond to line currents of different duration to effect the actuation of the switches.

In order to carry out my invention I make use of two wire or metallic circuits without grounds at the subscribers station.

Each subscriber signals and controls the central oflice apparatus merely by making and breaking the metallic circuit. 7

The nature of the switch controlling relays forms an important feature of my invention. These relays are of two types, the first being ordinary quick acting relays and the second sluggish or slow acting relays. It is by diflerentiating between short and long makes and breaks and the consequent action or inaction of one or the other set of relays that the switches are moved and their movements directed.

The switches which I make use of in connectionwith the invention may be of any convenient type, but are preferably of the typevwhich I shall hereinafter describe and shall illustrate in simplified form. It will be understood, however, that the construction of the automatic switches themselves forms no part of the present invention and will be described in detail merely for the sake of making clear the operation'of thesame by the co-action of the two types'of relays above mentioned.

More specifically stated, my invention comprises an ordinary common battery telephone set at each subscribers station, with a mechanical sender, or make and break device added; a pair of line-wires extending thence from the central ofiice,;where they terminate in a first ,selector switch indi-' enoids, which will respond in one direction with considerable rapidity, so as to be effectually actuated by short impulses, but which will not respond quickly in the other diIQC', tion. Thus I am enabled to send groups of short impulses separated by pauses of some length, during which the solenoids will have time to operate, each such pause or long impulse serving to prepare the workin part of the apparatus for the next series 0 short impulses.

No side switches are required in the switches of the present system, the changmg of the different local circuits being accomplished through relays or through the movement of the switch spindles themselves.

My invention isillustrated in the accompanying drawings, wherein I Figure 1 is a ont view of a type of austomatic switchwhich may be employed in this system.

Fi ure 2 is a bottom plan view of the contact anks thereof. I

Figure 3 shows a subscribers station and the central office end of the subscribers line. Figure 4- shows a first selector switch.

Figure 5 shows a second selector switch. Figure 6 shows a connector switch. Referring to Figure -1, -"the switch Z has a frame 1', carrying .the contact banks 2, a spindle 3, vertical magnet E, a rotary magnet D, and a release magnet W. The spindle carries the wipers 10 to co-operate with the contacts in the banks 2 and is fitted with a rotary ratchet 9 and a vertical ratchet 8, the former engaged by a pawl actuated by .the magnet E, and thelatter by a pawl underthe controlof the ma at D. A detent pawl 11 has two arms which engage both the rotary and vertical ratchets and are lifted therefrom when it is desired to release the switch by means of a link 12 on the armature lever 14 of the release magnet W. This magnet becoming energized pushes forward the link 12 until it engages a pin 15 on the upper or bellcrank arm of a double detent 11, and 'when the magnet is de-energized the-retracting spring 16 throws over the pawl to disengage it from the ratchets, the eby allowing the spindle to drop and rotate to its normal position. The spindle is provided with a cap 22 in which is a coiled spring having one end secured to the spindle andthe other to a rod 23, journalled on the spin dle at one end and on a' post 24 atthe other. Attached to the spindle is a stop arm 2'5.- These parts operate as follows: Sliding on the post 24, the parts 23 and 25 permit vertical movement of the switch and when the spindle is down so the wipers, are clear, the spring in cap 22 turns the spindle around from any angular position in which it.v may be, to the zero position, with the stop arm 25 against the lip on the arm 23, when the detent 11 is lifted.- Figure 2 is a bottom plan view, showing the switch banks 2 and the wiper arm 10. The contacts are arranged in vertical rows, forming a portion of a cylindrical surface whose axis is in the spindle.

Referring now to Figure 3, the subscribers station A is equipped with apparatus usual in common battery systems, of the transmitter T, receiver R, hook ringers Q and-condenser C. In addition to these I provide a sender O. which is a simple make and break device with one pair of springs o, 0', which are normally in contact with one another. siring to send a number, turns the handwheel 0 and the pins 0 then passing for-' wardly over'the spring-o do not break its contact with spring 0, but when the subscriber has set the proper number-and the hand-wheel returns to its normal po'sition under the influence of a suitable Y tension magnet.

retardation coil I. The relay S controls a pair of solenoid relays A and Br The relay S and is a quick acting relay of the ordinary form and its armatures s and s are adapted to open and close circuits in response to the energization and de-energization of the A and B are the relays of the sluggish type heretofore mentioned. These relays are so designed that they will pull up quickly when energized but\will take some time to restore when they are lie-energized. In Figure 3 I have shown the relays A and/B as solenoids having cores at and 5 which are drawnup into thesole'noids when the latter are energized and which restore slowly be- The subscriber de-- ing held back by the ordinary retarding means. Secured to the bottoms of the cores a and 6?, respectively, are the insulating cam pieces a and b. The cam piece 5 is adapted when the relay B is deenergizedto engage the spring contact I) to open the contacts 6, b, and to close the contacts 6 b b. The insulating cam piece a is adapted when the relay A is de-energized to engage the spring contact a to open the contacts a a and when the relay A is energized to engage the spring contact a to momentarily close the contacts a, a? and the contacts at and a. A battery B is provided for supplying the necessary current for the operation of the relays and for talking purposes. 'A retardation coil I is placed in the circuit between the battery and the telephone set, while the condensers C, C" are inserted in the conductors34 and 2-5, respectively, to prevent battery flowing to the various switches.

Referring now to Figure 4, I have therein shown a first selector switch. consisting of the following: a spindle e. on which are. mounted the trunkwipers'z, a andthe test wiper 2% The springs 2 and .2 are controlled mechanically by the spindle Z, and in their normal position these contacts are open. The switch first making the rotary motion does not aifect these springs, but

provided with one extra tooth in the vertical ratchet, thus allowing one false move; ment in a vertical position before bringing the wipers in position with the rows in the contact banks, that is to say, each spindle requires two vertical movements to bring its wipers in contact with the first pair of contacts. -I use this false movement as a switching device for doing away with a complicated side-switch. The vertical relay S in operating, controls the circuit. of the magnet K. which causes the spindle to rotate. The relay D controls the circuit of the test magnet F, and also in conjunction with the relay F controls the vertical magnet L to insure one full step for the spindle Z.

Tlfe relay M is simply a bridge relay which becoming energized when an idle trunk leading to a second selector switch is found, disconnects the relays S and D from the trunk wires 4 and 5 through the medium of the switching contacts m m m, m, mt, m, m", m, controlled by its armature, thus giving a clear pair of wires for talking purposes. X is a low wound relay adapted to control a relea'semagnet W jointly with the relays S and D in a manner hereinafter explained.

Referring now to Figure 5 I have shown a second selector switch which is similar to that shown in Figure 4, with the exception is designed to make and break the current through these magnets and thus furnish a series of impulses for stepping up vertically the spindles of the first and second selector switches.

Referring now .to Figure'6, I have shown a connector switch, which consists of a spindle Z on which are mounted the wipers a" and 2 The wiper 2 1n thls case as well as forming the sleeve side of the talking circuit, also takes the place of a test wiper, the test magnet X being connected directly to it.

The relays S and 1) correspond to the relays S, S and D, D in the other switches. L is the vertical magnet whose function is similar to that of L and L in Figures 4 and 5. In addition to the set. of

springs controlled by the first step of the spindle Z I have added a set of'springs 3 a, 2 which require at least two vertical steps to be operated. ,Y 1s a rlnging relay controlled by the relay M and adapted to connect the generator G, through the -medium of the contact 2 to furnish ringing current for. the called line. The retardation coils I, I having bridged battery between their windings, furnish talking current to the called subscriber.

The operation of this system is as follows:

Referring to Figure3, the subscrlber at station A desiring to be connected withanother subscriber, first removes his receiver R, which closes the line circuit through the following path: B, 22, I, 2, H, R, T, 1-, 0, of,

3, S, ground to battery, and energizes the relay S, which attracts the armature s, closes the contact at s, which in turn closes the following circuit through the solenoid B battery B, 22, conductor 22, contacts a, s, solenoid. B, conductor 29, ground to battery. The core I) of the solenoid B now being drawn up, batteryis connected to the contacts 8 of the relay S by the following path: battery B. 22, 30, b, 23, The relay S at this time being energized, the'circuit' of the solenoid A remains open.

The subscriber at station A, after removing his receiver, sets his number-wheelo' to the desired number, and this wheel in running down makes and breaks the contact 0, 0, according to thenumber of impulses to be sent. These makes and breaks between the contacts, 0 and o affect the relay S at the central oflicc, and this relay in turn makes and breaks its contacts.-- .The making and breakingpfthe contacts 8 and a, a, a.

8* causes the solenoid A to become energized and draw up-the corea. The makmg and breaking of the contacts 8 and s keeps the solenoid B energized, while the making and breaking of the contacts s and 5 sends in impulses over the conductor 20, contacts b", b, conductor 21, and the'trun'k-wire 41:0 the first selector switch. Theseimpulses of course correspond to the makes and breaks of 'the contacts 9 and 0'. After this first set of impulses has been sent in, the relay S remains energized and the core a of the solenoid A drops, and in dropping it momentarily closes together the contact springs This places battery on the trunkwire 5 by the following path: ground side of battery, battery B, conductor 22, contacts s and s, conductors 24, '28, contacts a, a, conductors 27, 32, trunk-wire 5, and on the line-wire 3 asv follows, ground side of battery, battery B, conductor 22 contacts 8, s, conductor 28, contacts a", a, a, conductor 26, line 3. Battery being thus momentarily placed on the trunk-wire 5 operates the control relays. in the various switches as described hereinafter.

Referring to Figure 4, the first set of im pulses corresponding to the thousand numeral of the desired line coming in over No. .4 side of the trunk through contacts m, m, of of the relay M and conductor 36, relay S, toground, operates the relay S, which in turn closes the circuit of the rotary magnet K by the following path: ground, 8, 8", 40,

f '37, K, 44, to battery B. This magnet through the contacts m, m of the relay M,

thence by conductor 52, relay D" to ground,

operates the, relay D, which in turn momentarily closes the circuit of the relay F,

llO

at the contact d, from ground d. conductor d, relay "-F, conductor 45, battery,

ground, and this relay F operating mo-- mentarily closes the circuit of the vertical magnet L by the following path: ground, f, f, 35, d, (5 ,51 to battery B. The operation of the vertical magnet L causes the spindle Z to step up 'vertically one step which closes the contact springs z and 2". It will be noticed that when the contacts d and d of the relay D are closed during the momentary impulse over wire 5, the contacts (l and (l? are opened, disconnecting the constantly rotating interrupting machine V, (Figure'fi), which would otherwise be connected with the vertical magnet L over the following path: ground side of battery (Figure 5), battery, V. conductor 48,

thence on to conductor 48 (Figure 4) to cl,

35, L, 38, f and ground. This circuit being bro en, as stated, at (i d pre- *advance or step the spindle one step by a suitable setscrew. The switch frames only contain the movable parts and their operating magnets, as the relays controlling the various magnets are mounted on relay racks in dust-proof cases, as usual in standard practice. a selector switch and a connector switch is the circuit. wiring and relays. Figures 4 and 5 showing selector switches and Figure 6 showing a connector switch, as heretofore stated. This in itself, although forming no part of the present invention, is a very desirable feature, for all the actual working.

parts are uniform and any switch getting out of order can simply be drawn out of its case or removed from the rack and another put in its place. This avoids the necessity of having to carry in stock a certain number of first selector, second selector and connector switches for repair work.

Referring again to Figure 4, after the controlling impulse comes in and the spindle is advanced one step the wipers reston the first contacts leading to a second selector switch of the desired thousand.

It will be obvious that upon the first vertical step of the spindle Z, the contacts 2*, z are closed. When the rela F .which has been momentarily energized rops back, the relay M is then actuated, current flowing over the following path: ground side of battery, battery B, conductors 45, 47, contacts z, 2 conductor 39, relay M, conductors 41,

contacts 7", f, ground, relay F having released its armature F. The armature of the relay M in pulling up opens the contacts mr m', m m*, mP-m", and closes the contacts m'-m fin -m and m"m Thectest contacts 2 Figure 5, upon which th vwiper 2 Figure 4, rests, may be busy or grounded over the following path: ground side of battery, battery B, conductor 45, relay F, conductor 42, contacts m, m conductor 43, wiper a contact 2 (see Figure 5), one of the other contacts connected in multiple with .2 back upon a test wiper of the trunk which happens to be busy (see Figure 4 again) and to ground through the circuits of the switch of the The only difference between .ready traced busy trunk which is identical with the switch shown in Figure 4 over the corresponding conductor 43, contacts m", m (since the corresponding relay M of the busy trunk has pulled up, closing these latter contacts) conductor 50, relay X and ground. It will be noted that the relays F and X of the busy trunk are in series in the test circuit. The relay F of all the switches is wound to a high resistance and the relay X to a relatively low resistance. The test current is consequently cut down so that the relay X does not pull up and the busy trunk is in no wise disturbed. The relay F in thiscase remains energized as shown and the circuit of the vertical magnet L remains closed through the 'interrupting machine V, through the following path; (see Figure 5) ground side of battery, battery, interrupter V, conductor 48, conductor 48 (see Figure 4), d d conductor 35, L, 38, f", f, and ground, and the switch will continue to step up vertically until an idle contact is found, that is to say one free from ground. As soon as such a contact is found, the relay F becomes de-energized by the breaking of the test ready traced, and the circuit of the relay is closed by the path ali. e., battery B, 45, M, 41,

47, 2 2 39, f, f, to ground. The

relay M now becoming energized attracts its armature, disconnects the two relays S and D, the former by opening the contacts m, m, and the latter by opening the contacts m3 and m and connects the trunkwires 4-6 and 5-7, by closing the contacts m m, m* m respectively, provid-' ing a continuous talking circuit from the calling subscriber to an idle second selector switch. -'The energization of this relay M also disconnects the relay F from the test wiper, 2 by the breaking of the contacts m m" and in its place connects the back release relay X b the following path: 2 43, m, m", 50, to ground. This relay is low-wound as alrea y stated, so as not to respond when the wiper of some other switch passes over a multipe of the contact upon which the test wiper 2 rests.

The calling subscriber now being connected to a second selector switch sends in the second set of impulses which operates the second selector switch, Figure '5, in a manner identical with'that of the first selector switch, Figure 4, the lines 4--6 and 5-7 being connected through the actuation of the relay M in Figure 4, as already shown. This second set of impulses oper ates the relay S in Figure 5 in precisely the manner described in connection with the firstv set of impulses. The impulses from the relay S come over the lines 4-6, wiper z', contact 2, in Figure 5, conductor 8, contacts m f, m", conductor 67, relay 8*,

12, line 12, conductor 81, relay and to ground. Relay S. in turn operates the rotary magnet K, current passing from ground, contacts 8 s, conductor 71, 'contacts f f conductor 59, K, conductor 57, battery, ground, causing the spindle Z to rotate and bring the wipers 2 2 all opposite or in line with a row of contacts leading to connector switches of a desired hundred. A controlling impulse comes in over the No. 9 side of the trunk, being sent by the closing of the circuit momentarily by the retraction of the core of the solenoid A in Figure 3, which closes the contacts a (1', thereby sending an impulse from battery B, in Figure 3,conductor 22, contacts e,s',conductors 24, 28, contacts a a, conductor 27, conductor 32, line 5,-line 5 (Figure 4 the contacts mfi-m, which are now close hne 7, wiper 2 contact 27 (Figure 5), line 9, contacts m -m conductor 68 D" to ground. This operates the relay iDZwhich inturn advances the switch one step, bringing the wipers to rest on' the first set of contacts leading to a connector switch of the desired hundred. The spindle Z continues to step up until the test wiper z finds an idle contact, for the reason explained in connection with the first selector switch.

As soon as such a contact is found the relay M becomes energized and the calling subscriber is connected through to an idle connector switch of the desired hundred, and a relay X is connected to the test wiper 2. The circuits of this switch. with the exception of the back release connections, are identical with that described in connection with Figure 4, so I have not attempted to go into detail. The release circuit will be described later.

Referring to Figure 6, the calling subscriber now being connected to a connector switch sends in a third set of impulses which come from the relay S in Figure 3 over the conductors 4, 6, 8, 10, (the relay M having operated to connect the lines 8l0 in the manner precisely the same as described for the connection of lines 46 by the relay M in Figure 4) wiper 2, contact S, ground. These impulses coming in over No. '12 side of the trunkoperate the relay S, which in turn closes the'circuit of the rotary magnet K by the following path: ground, 07, d1? 12 11 91 zs m 92 23 24 99 KI, 98, 94, to battery B. This magnet-K operating causes the spindle Z to rotate. and bring the wipers a", 2? in line with a row containing the contacts of the desired line. The controlling impulses coming in over the N o. 13 side, ofv the trunk from the momen tary closure of thecontacts a, a of the relay A in Figure 3, and over the lines 5,7, wlper a, contact a" (Figure 5 conductors 9, 11, wi r 2, contact z, operates the relay which in turn closes the circuit from control of the relay then to the sleeve side of the line 2,

of the vertical magnet, U by the following ath: ground, 8%", 8 d d 96, 2?, z, 100, L 98, 94 to battery B. The operation of this magnet L causes the spindle Z to take one vertical step, which opens the contacts 2 2 disconnecting the magnet K, closing the contacts 2 2 and connecting the magnet L in its place. The calling subscriber now sends in the fourth set of impulses, which coming in over No.v 12 side of the trunk operates the relay S, which now in turn closes the circuit of the vertical magnet L by the following path: ground, (1 9, d", 8 8 91, m m, 92, z, 100, L 98, 94, to battery B. The operating of this magnet L? causes the spindle Z to step up and bring the wipers to rest on the contacts of the desired line. After the first impulse of the fourth set comes in the contacts a, z are broken, removin the in ct L connecting the relay M b closing the contacts z, z. The contro ing impulse coming inover N0. 13 side of the trunk after the fourth set of impulses operates the relay D, which now in turn closes the circuit of the relay M by the following path: ground, 8, s, (1,0, 96, 2 9, a, 95, M, 88, 87, 86, to battery B.--i The relay M now becoming-energized locks itself through the contacts m, m, and the wire 90 to ground through the contacts of the relays S and D. This controlling impulse operating the relay .D 'also momentarily placesthe relay X in a test position by the following path: batteryB, 86, d, d", 85, X 93, 19, to wiper z. 'If the desired line'is in use, and consequently has its circuit completed through the switch-hook H at the substation, then the circuit thus traced to wiper z woul be continued through the contact at the B and in its place terminal of the desired line (see Fiin'e 3) rough the telephone apparatus H; R, T, 1, contacts o o, 3, S, and ground. The release rela 2 would then draw up its armature closing. the contacts ea -w", and current would flow from the battery 86, d", d", 85, W conductor 84, contacts 8 a". conductor- 83, w, w, to ground. The release magnet would restore the testing switch to its normal position.

In this particular case we will take it for gianted that the line is not busy. The relay being energized, connects the calling subscriber through to the contacts of the desired line. connecting the talking circuit, it also opens the contacts m and vertical magnet L and in its place connects the ringingrrelay Y by closing thecontacts m", m. his ringing relag is also preferably sluggish in its action. be calling subscriber now being1 connected to the desired line again turns is hand-wheel sending in m", disconnectir g the an additional set of impulses, operating the relay S which now in turn operates the ringing relay Y in the following -manner.

When the relay S pulls up, the contacts ground. This ringing relay in operating disconnects the calling end of the trunk and connects generator current to the called end notifying the desired subscriber that he 1s wanted. The called subscriber is supplied with current for talking through the two retardation coils 1, 1 by the following path: to battery, conductors 86, 87, T 102, 15, m, m, 16, 19, sleeve wiper 2 subscribers circuit, tip wiper 2 f, conductors 18, 17, contacts m, m, conductors 14, 101, 1, D ound.

At the end of the conversation the calling subscriber upon hanging up his telephone, effects the release of the. various switches in the following manner:

During conversation the core of the solenoid B remains drawn up, while that of solenoid A remains down. The calling subscriber upon hanging up his telephone opens the line-circuit, deenergizing the relay S, whereupon the solenoid A at once draws up its core a, while the core I) of the solenoid B begins to drop, and as soon as it assumes its normal position battery is connected to bot-h sides of the trunk by the following path: battery B, a a, b, I), 6 21, 31: After it has assumed its normal position, the

contacts 6, b are broken, opening the circuit of the solenoid A whose core a thereupon begins to drop, and as soon as it assumes its normal postion the contactsafi, a, are broken and battery is removed from the trunkwires 4: and 5, respectively. It will be seen from this method of operation that the" joint action of these solenoids places battery momentarily on both sides of the trunk for releasing. a

Referring now to Figure 6, this momentary impulse coming in over both sides of the trunk operates the relays S and D simultaneously, which closes the circuit of the release magnet W by the following path battery B, 86, 03 d", 85, W, 84:, a 8

15 $2 2, and in Figure 5, 2 63, m m", X to ground. The operation of magnet W restores the switch to its normal position. The simultaneous operation of the relays S and D also releases the locking relay M by removing ground from the contact m. In Figure 5 the rela X being in series with the magnet W igure 6, as already described, also becomes energized and attracting its armature closes the circuit of the release magnet W' by the following path: battery B, W, av w, 66, 2 and in Figure 4, a 43, m, m 50, X to ground. The operatery stores the first selector switch to its normal tion of the release magnet W restores the second selector switch to its normal position and the spindle Z coming to rest opens the contacts 2 e and releases the relay M The relay X, Figure 4, being in series with the magnet W, Figure 5, also becomes energized and attracting its armature closes the circuit of the release magnet W by the followin path: ground, av, 02, W, 19, to bat- The operation of this magnet reposition, and the spindle Z coming to rest ld/pens the contacts 2 2 releasing the relay It will be seen from the description of the foregoing circuit that the releasing of the various switches is controlled directly from the distributor of thecalling subscriber and not as ordinarily from the connector switch. In place of sending an impulse over both sides of the trunk for releasing, I may operate the release magnets directly by the two solenoids, in various ways.

Having thus described my invention what I claim is:

1. In an automatic telephone exchange system a plurality of subscribers stations and metallic circuit lines extending thence to a central office, automatic switching apparatu's for interconnecting the lines at the central oflice, a source of current connected in the metallic circuit of a subscribers line, means at the substation to make and break the said metallic circuit at will, the makes and-the breaks being of varying but predetermined duration, and means at the central oflice responsive to such makes and breaks in the metallic circuit to actuate, control and release the automatic switching apparatus and also to ring the wanted subscriber, substantially as described.

2. In a telelphone exchange system a plurality of subscribers stations and metallic circuit lines extending therefrom to a central office, automatic switching apparatus having one or more actuating magnets and release magnets, and a common source of current supply for the lines at the central ofiice, a telephone at each substation adapted to be bridged across the metallic" circuit and to derive current therefrom for talking purposes, and means at each substation to make and break the metallic circuit in accordance with any desired or necessary code signal, together with means at the central ofiice responding to the makesand breaks of 'the metallic circuit and adapted to actuate the automatic switching apparatus, to shift the control of the actuating means to that end as required, to ring the wanted subscriber, and finally to release and clear out the apparatus, substantially as described.

3. In a telephone exchange system a plurality of subscribers stations and metallic circuit lines extending thereform to a censaid relays res system,

tral office, automatic switching apparatus having one or more actuating magnets and releasemagnets, and a common source of current supply for the lines at the central office, a telephone at each substation adapted to be bridged across the metallic circuit and to derive current therefrom for talking purposes, and means at each substation to make and break the metallic circuit in accordance with any desired or necessary code signal, together with means associated with each line at the central oiiice' responding'to the makes and breaks of the metallic circuit and adapted to actuate the automatic switching apparatus, to shift the control of the actuating means to that end'as required, to ring the wanted'subscriber, and finally to release and clear out the apparatus, substantially as desired. 7

4. In a telephone exchange system a plurality of subscribers lines and line-circuits extending therefrom to a central oflice, -a first selector switch associated with each line at the central office, auxiliary switches in groups accessible from said first selector switches and serving to trunk a calling line through selected groups of switches to the line wanted, means at each substation for making and breaking the line-circuit, and relays associated with each line and connected therewith between the substation and the first selector switch, said relays responsive to the makes and breaks in the linecircuit and controlling the local circuits of the first selector switch and through it when inuse controlling the circuits of selected auxiliary switches, all substantially as described. v

5. In a telephone exchange system a pluralityof subscribers lines and metallic talking circuits extending thereform to a central oflice, a first selector switch associated with each line at the central ofiice, auxiliary switches in groups accessible from said first selector switches and serving to trunk acalling line through selected groups of switches to the line wanted, means at each substation 'for making. and breaking the talking circuits, and relays associated with each line and connected therewith between the substation and the first selector switch, onsive to the makes and breaks in the inc-circuit and controlling the local circuits of the first selector switch and throu h it when in use controlling the circuits 0 selected auxiliary switches, all substantially as described.

6. In an automatic telephone exchange a subscribers station and a central offic'e with a metallic line circuit interconnecting them, automatic switching apparatus at the central office, and means for making and breaking the metallic circuit at the subscribers station, .means connected to the subscribers metallic talking circuit and becoming active upon the closure of the same at the subscribers station, for placing the automatic switching apparatus under operative control of the line, means responsive to makes and breaks only in the talking circuit to actuate said switching apparatus, to shift the control of the same, and to ring the wanted subscriber when selected; and means responsive to a final and continued break in the talking circuit to restore said switching apparatus to its normal position and render it inactive as long as the line-circuit remains broken, substantially as described.

7. In an automatic telephone exchange system a pluralit of subscribers stations and a central 0 ce, with two-wire linecircuits interconnecting them, a series of automatic switches for interconnecting the lines, means at each sub-station for producing current changes in the two wires of its line, means at the central ofiice responsive to such changes to actuate one or more of said automatic switches, successively, so as to build up a link connection with a line' wanted, and means controlled by the calling subscriber over his line for restoring the first of said automatic switches and through the same for restoring the successive links by sending forward the necessaryimpulses therethrough, substantially as described.

8. In an automatic telephone exchange system, subscribers two-wire lines with substation controlling apparatus, and central ofiice automatic switches, each switch comprising an actuating member or spindle, contact devices moved thereby to effect the desired connection, and controlling devices for said switch comprising magnets and relays only, separate local circuits for the several magnets, adapted to be selectivgly energized, to produce the proper moveme of the contact devices, a switch circuit constituting a continuation of the subscribers line circuit, and relays responsive to current in said circuit and adapted to vary the connections 'in the local circuits so as to selectively. shift the control thereof as and for the purpose stated, substantially as described.

9. In a telephone exchange system, a subscribers metallic two-wire line circuit, an

automatic switching set comprising blanks of resting contacts arranged in a plurality of rows, co-operating active or. movable contacts having motion in two directions for effecting connection with the bank contacts, working magnets for actuating the movable contacts in each direction, means responsive to changes inthe subscribers metallic circuit for energizing said magnets, and controlling relays also responsive to changes in the, me-

tallic circuit and adapted to shift the air cuits of the working magnets, whereby no mechanical side switches are required, substantially as described.

10. In an automatic telephone exchange system, a plurality of subscribers metallic circuit lines without grounds, a telephone talking set at each substation, and a signaling device also at each substation for making and breaking the metallic circuit, a relay connected with the line at the central office, and a source of current for the line, together with a pair of branch circuits controlled by said relay, one branch being closed when the relay is energized and the other when it is deenergized, a pair of sluggish relays in said branches, adapted to pull up their arma tures but not to retract the same on short current changes, automatic switches for .in-'

I as described.

11. In a telephone exchange system, a line circuit and automatic switches for connecting the same with other circuits, a relay responsive to all changes in the line and having front and back contacts, with a pair of sluggish relays connected to said contacts respectively, and controlling circuits for said switches jointly controlled by said relays, substantially as described.

12. In a telephone exchange system, line circuits, and automatic switches for interconnecting them, with means for controlling said automatic switches comprising a fast relay responsive to line current, and a pair of slow relays, said fast relay having contacts adapted when it is vibrating to energize both slow relays, when it remains attracted to energize one slow relay only and when it is retracted to energize the other slow relay only, substantially as described? 13. In a telephone exchange system, me-

tallic line circuits, automatic switches for interconnecting the same, and means for controlling said switches comprising a fast relay and a pair of sluggish relays controlled thereb for each'line, together with local actuating and release circuits extending from said relays to said. switches, substantially as described.

14..The combination of a line circuit, a source of current connected thereto, means for establishing in said circuit either a continuous or a rapidly interrupted current from said source, with a line relay acting quickly both on makes and breaks, front and back contacts closed b said. relay when energized and deenergize respectively, an auxiliary relay connected to each ofsaid contacts, "each of said auxiliary relays adapted to pull'up its/armature or core quickly, but to release the same slowly, automatic switches, and controlling circuits therefor passing through contacts on the sluggish relays and controlled therethrough.

shifted, controlled, and released, andv ringing means also actuated through the line by said relay, substantially as described.

17. A telephone exchange system compris ing a subscribers station having a transmitter, receiver, call-bell and call transmitting device, a two-conductor circuit extending from said station, a plurality of interconnecting link-circuits, other subscribers lines, associated automatic step-by-step switch mechanism for selectively extending the two-conductor circuit through said link circuits to said other subscribers lines, means for advancing and releasing said mechanism by variations of current transmitted over said two-conductor circuit, means whereby conversation may be held over said circuit, and means for actuatingsaid callbell by current over said circuit.

18. A telephone exchange system comprising a subscribers station having a transmitter, receiver, call-bell, and call transmitting device, a two-conductor circuit extending from said station, interconnection linlccircuits, other subscribers lines, automatic step-by-step switch mechanism for selectively extending said twoconductor circuit through said link-circuits, to said other subscribers lines, a central source of current, means for advancing and releasing said mechanism by variations in said tWo-cOnductor circuit of current derived from said source, means for energizing said transmitter over said circuit from said source, and means for actuating said call-bell-by current over said circuit.

19. A telephone exchange system comprising a two-conductor circuit, associated automatic step-by-step switch mechanism having waiting contacts divided into groups and a co-operating moving contact, and means responsive to variations of current transmitted over said circuit to advance said moving contact both to a desired group of waiting contacts and then to adesired contact in that group.

20. A telephone exchange system comprising a two-conductor circuit, associated auto-' matic step-by-step switch mechanism hav-.

ing waiting contacts divided into groups and a co-operating moving contact, means I divided into groups and a ing a control clrcuit responsive to variations of current transmitted over said circuit to advance said moving contact both to a desired group of waiting contacts and then to a desired contact in that group, and means responsive to a change in the current condition in saidcircuit to bring said moving contact to its normal position.

21. A telephone exchange system comprising a two-conductor circuit, associated automatic switch mechanism having waiting contacts dividedinto group and a co-operating moving contact, means outside of said mechanism for rendering some of said waiting contacts busy, means for advancing said moving contact to a desired group of waiting contacts in response to variations of current transmitted over said circuit, means for starting said moving contact in search of an idle contact in that group in response to another current variation in said circuit of a different character, and means for continuing the movement of the moving contact in such search and stopping it only when an idle waiting contact is found.

22. A telephone exchange system comprising a two-conductor circuit, associated automatic switch mechanism having waiting contacts divided into groups and co-operating moving contact, means outside of said mechanism for rendering some of said waiting contacts busy, means for advancing said moving contact to a desired group of waiting contacts in response to variations of current transmitted over said circuit, means for starting said moving contact in search of an idle contact in that group in response to another current variation transmitted over said circuit, and means for continuing the movement of said-moving contact in such search and stopping it only when an idle waiting contact is reached.

23. A telephone exchange system comprisassociated automatic switch mechanism having waiting contacts co-operating a primary magnet and asmoving contact,

for stepping sa1d moving sociated means I contact to a desired group of waiting conta c-ts, a secondary magnet and associated means for stepping'said moving contact to a desired contact in that group, a sluggish relay for controlling the operating circuit of said secondary magnet, a quick-acting relay for controlling said primary magnet and said sluggish relay, means for energiz;

' ing and de-energizing said quick-acting recircuit" to operate said lay by making and breaking said control primary stepping a 2" I magnet,,and energize and mauitaln sa1d -slug g i sh .j1 elay energized during such operation and then to d'e-energize said sluggish relay to operate said secondary magnet.

24. A telephone exchange system compriscooperating moving switching means having waiting contacts divided into groups and a co-operating waiting contact, primary means for stepping said moving contact to a desired group of waitin'g contacts, secondary means for stepping said moving contact to a desired waiting contact in that group," and quick and sluggish relays controlled over said control circuit, the former to cause the operation of said primary means and the latter to initiate the operation of said secondary means. V

25. 'A telephone exchange system comprising a subscribers station having a transmitter, receiver, call bell, and call transmitting device, a two-conductor circuit extending from said station, a plurality of interconnecting link circuits, other subscribers lines, associated automatic step-by-step switch mechanism for selectively extending the two-conductor circuit through said linkcircuits to said other subscribers lines, means for advancing said mechanism in response to current variations transmitted over said two-conductor circuit, means for releasing s'aid mechanism by opening said circuit, means for holding conversation over said circuit, and means for actuating sai call bell by current over said circuit.

26. A telephone exchange system compris ing a two-conductor telephone circuit, associated automatic switch mechanism having waiting contacts divided into groups and a contact, means outside of said mechanism for rendering some 0 said Waiting contacts busy, means for. advancing said moving contact to a desired group of waiting contacts in response to successive intermittent current variations transmitted over the two talkin conductors of said circuit, means for starting said moving contact in search of an idle contact in that group, and means for continuing the movement of said moving contact in such search and stopping'it only when an idle waiting contact is reached.

27. A telephone exchange system comprising a two-conductpr circuit, associated automatic switch mechanism having waiting contacts divided into groups and a cooperating movable contact, means outside of said mechanism for rendering some of said waiting contacts busy, a primary electromagnet, a secondary electromagnet, means for causing interruptions of said two-conductor c rcuit, whereby said electromagnets step sa1d movable contact to a desiredgr up and then to an idle waiting contact e' group, and means for ausingrotatio-n 0 ,said switch mechanism responsive to a jfurther"fl interrup-,

tion of said, two-conductor circuit; 2'8. In a telephone system, the .ciu'nbina and step-by-step actuated switches, connections between said switches, line circuits for successively controlling said switches, a subscribers device for intermittently closing the line to establish said circuits, each line circuit including the. two sides of the line in series, and means for supplying current over the line to operate said switches, and for talking purposes also.

29. In a telephone exchange system, the combination of telephone lines, automatic connectors less in number than said telephone lines, selectors less in number than the telephone lines, subscribers individual switches corresponding in number to the telephone lines, subscribers devices for closing the lines to control said individual switches and selectors and connectors by transmitting a varying number of impulses for each digit of the called number, line circuits by which the said individual switches and selectors and connectors are controlled, each line circuit including the two sides of a calling teleof a calling telephone line, a called telephone line, automatic step-by-step switches for trunking the callin line into connection with the called line y theautomatic selection of trunks in predetermined groups,

means for opening the calling line to release or restore the said switches, the said switches provided with release mechanism responsive to the opening of the calling line to release the switches either before or after the called subscriber answers, and means for supplying current over the telephone lines to operate said switches, and for talking purposes also.

31. In a telephone system, the combination of telephone lines, trunk-lines, automatic self-contained step-by-step operated trunk selectors for selecting idle trunlrl ines, automatic self-contained step-by-step operated connectors for completing connection with the called telephone lines, line circuits for controlling said selectors and connectors, said line circuits each including the two sides of a calling telephone line in series, and means for supplying current over the telephone lines t9 operate said selectors and connectors,'a'nd for talking purposes also.

32. In a telephone system, the combination of a plurality of switches each adapted to both vertical and rotary step-by-step motion in response to one. or more impulses for the called number, telephone lines, line circuits for successively controlling the said switches to extend connection from acalling line to acalled line, said line circuits each including the two sides of the calling lines in series, and means for supplying current over the telephone lines to oper ape said switches, and for talking purposes a so.

33. In a telephone system, the combination of-a plurality of automatic switches, telephone lines, line circuits for'sucoessively controlling said switches to extend connection froma calling line to a called line by the transmission of a varying number of impulses for each digit of the called number, means for opening the lines when the subscribers hang up their telephones, means directly responsive to the opening of a connected telephone line for initiating the release of all switches between the lines of calling and called subscribers, and means for supplying current over the telephone lines to operate said switches, and for talking purposes also.

34. In a telephone system, the combination of trunk lines, an automatic step-bystep trunking switch provided with trunkselecting mechanism, and with releasing mechanism, a telephone line, a subscribers releasing device for said telephone line, line circuits for controlling the operation of said switch,.said circuits each including the two sides of the telephone line in series, the release mechanism of said switchbeing directly responsive to a subscribers releasing device, and means for supplying current over the telephone line to operate said switch, and for talking purposes also.

85. In a telephone system free from operating grounds at the substations thereof, the combination of telephone lines, automatic trunking and connecting switches, line circuits by which a calling subscriber successively controls a plurality of said switches to extend connnection to the called subscribers line by the transmission of a varying number of impulses for each digit of the called number, said circuits each including the two sides of a calling telephone line in series, subscribers releasing devices for the telephone lines, means immediately responsive to said releasing devices for releasin or restoring said switches to normal condition, and means for supplying current over the telephone lines to operate said switches, and for talking purposes also.-

36. In a telephone system free from operatin grounds at the substations thereof, the com ination of telephone lines, automatic switches, line circuits for successively controlling a plurality of said switches to extend connection to a called subscribers line, by the transmission of a varying number of impulses for each digit of the called number, means for transmitting impulses over ing the two sides of a calling telephone line in series, each switch provided with a switch shaft adapted for both vertical and rotar motion, means carried by the shaft of eacli switch for extending connection in the direction of the called subscriber, and means for supplying current over the telephone .lines to operate said switches, and for talk ing purposes also. i

37. In a telephone system, a subscribers station, a step-by-step vertical and rotary switch allotted to. said station, means whereby the said switch may be released at any stage of the caH,by simply breaking or opening the line circuit, and means for supplying operating and talking current from the central station, substantially as set forth.

38. In a telephone system, a called line, a connector provided with an element having vertical and rotary step-by-step motion to find the called line, release mechanism for restoring the connector to. normal position, and a single line relay operative to control the vertical and rotary motion and the release of said connector.

39. In a telephone system, a called line, a connector provided with line wipers having vertical and rotary ,Step-by Step motion tofind the called line, and a-single line relay operative to control the vertical and rotary" motion.

40. In a telephone system, the combination of a called line, -a conne ctor provided with an element having vertical and rotary stepby-step motionto find the called line, release mechanism for restoring the connector to. normal position, a single line relay operative to control the vertical and rotary motion and the release of said connector, and means for controlling said relay over a metallic line circuit. I

41. In a telephone system, the combination of a called line, a connector provided with line wipers having vertical and rotary stepby-step motion to find the called line, a single line relay operative to controlthe vertical and rotary motion, and means for controlling said relayover a metallic line circuit.

42. In a telephone system, the combination of a connector provlded with an element having vertical and rotary motion to find the called line, release mechanism for restoring the connector to normal position, a sing] line relay operative to control the vertica and rotary motion and the release 'of said connector, and a calling mechanism to which said relay is responsive, said mechanism requiring a separate manual'adjustment thereof for each digit of the called number, adapted to transmit suitable current for onecdigit before adjustment thereof for the next digit. 43. In a telephone system, the combinatlon of a connector provlded with line wi ers having vertical and rotary motion to fin the called line, a single line relay operative to control the vertical and rotary motion, and a calling mechanism to which said relay is responsive, said mechanism requiring a separate manual adjustment thereof for each digit of the called number, adapted to trans-' mit suitable current for one digit before adjustment thereof for the next digit.

44'. In a telephone system, the combination :of a-metallic line circuit, a connector provided with an element having vertical and rotar motion to find the called line, release mec anism for'restoringthe connector to. normal position, a singleline relay operative to control the vertical and rotary motion and the release of said connector, and means for controlling said relay over said metallic line circuit, comprising a calling mechanism to which said relay is responsive, said mechanism requiring a separate manual adjustment thereof for each digit of the called number, adapted to transmit suitable current for one digit before adjustment thereof for the next digit.

v 45. In a telephone system, the combination of a metallic line circuit, a connector provided with line wipers having vertical and rotary motion to find thecalled line, a single line relay operative to control the vertical and rotary motion, and means for controlling said relay over said metallic line circuit, comprising a calling mechanism to which said relays responsive, said mechanism requiring a separate manual adjustment thereof for each digitof the called number, adapted to transmit suitablecurrent for one digit before adjustmentthereof forthe next di 't. i

iii. Atelephone exchange system comprismg a two-conductor circuit, associated automatic switch mechanism having Waiting contacts divided into groups and a cooperatin moving contact, means outside of said mec anism for rendering some of said waiting contacts busy, means for advancing said moving contact to a desired group of wanting contacts in response to a variation of current transmitted over said circuit, means for starting said moving contact in search of an idle contact in that group in response to another current variation transmitted over said circuit, and means for continuing the movement of said moving contact in such a search and stopping-it only when an idle waiting contact 1s reached.

47. A telephone exchange system comprising a telephone line extending from a central ofiice to a distant (point, a source of current in circuit withsai line, normally controlled means at said distant point for interrupting the circuit of the line, other telephone lines, an electrically controlled switch at the central ofiice for establishing connection between said line and said other lines, active contacts for said switchconstituting terminals for said line, passive contacts for said switch constitutmg terminals for sa d other lines, restormg means for said switch, means responsive to short making and breaking of the circuit of said line for causing a primary operation of said switch, and means responsive after connection is established with a desired line whereby a long interruption of the circuit of said line will cause a secondary operation ot'said switch.

48. A telephone exchange system comprising a two-conductor telephone circuit, associated automatic switch mechanism having waiting contacts'divided into groups and. a cooperating moving contact, means outside of said mechanism for rendering some of said waiting contacts busy, means for advancing said moving contact to a desired group of waiting contacts in response to current variation transmitted over the two talking conductors of said circuit in series, means for starting saidv moving contact in search of an idle contact in thatgroup, and means for continuing the movement of said moving contact in such search and stopping it only when an idle waiting contact is reached.

49. In telephone system, the combination with an automatic switch provided with operating and restoring magnets, of a closed: controlling circuit for said switch, means for causing interruptions of said circuit, a plurality of quick acting relays responsive to said interruptions, and circuits for said magnets controlled by said relays.

50. In a telephone system, the combination with a metallic line circuit extending to a central exchange and means for transmitting current impulses over the two sides thereof in series, of a progressively movable switching mechanism provided with a plurality'of motor magnets, and a plurality of quick acting relays in said switch responsive to said current impulses for controlling said magnets.

51. In a telephone system, the combination with a metallic line circuit extending to a central exchange and means for transmitting current impulses over the two sides thereof ,in series, of a progressively movable switching mechanism provided with a plurality of motor magnets, and a plurality of relays in said switch for controlling said magnets, each of said relays responsive to each of said impulses.

' 52. In a telephone system, the combination with a metallic line circuit and means for transmitting current impulses over the two sides thereof in series, of an auotmatic selector switch having primary and secondary selecting functions, primary and secondary motor magnets for operating said switch to perform said functions, and a plurality of relays for controlling said magnets, saidrelays each responsive to each of said impulses.

'53. 'In a telephone system, the combination or long interruptions in said circuit, anda plurality of relayseach responsive to interruptions of both kinds for controlling said magnets.

54. In a telephone system, the combination with an automatic switch and a controlling circuit therefor, of means for producing current impulses in said circuit, operating magnets in said switch responsive to said impulses, switching means for controlling the circuits ofsaid operating magnets, and a pair of relays responsive to said impulses for controlling said switching means.

55. In an exchange system, the combination with a plurality of metallic line'circuits extending from substations to a central ofiicc, of a plurality of line selectors at the central otiice switch mechanism at each substationadapted to produce current variations in the line circuit thereof, and means at the central ofiice responsive to said 'variations adapted to cause a. series of said selectors operating in succession to connect said metallic line circuit with another for telephonic communication.

56. In a telephone exchange system, the combination with a plurality of line circuits,

each comprising two conductors extending from a substation to a central oflice, of group and individual line selectors at the central ofiice, switch mechanism at each substation adapted to produce current variations in the line circuit thereof, and means at .the central oflice responsive to said current variationsto cause a series of said selectors operating in succession to connect said line circuit with another for telephonic communication.

57.'In a telephone exchange system, the combination with subscribers line circuits, each comprising two conductors extending from the substation thereof to a central office, of switch mechanism at each substation for producing current variations in the line circuit thereof, and a series of selectors at the central ofiice operating in succession in response to said current variations and adapted thereby to interconnect such line circuit with another for telephonic communication.

58. In a telephone exchange system, the combination with a plurality of metallic line circuits, of means for producing current variations in said circuits, agroup selector switch and a line connector switch, said switches being adapted to operate in succession in response to such current variations to interconnect the said circuits for telephonic comunication.

59. In a telephone exchange system, the

combination with a'plurality of subscribers" 60. In a telephone exchange system, the

combination with a plurality of subscribers line circuits each comprising two conductors without ground connections at the substation thereof, of a switch. mechanism at each .substation adapted to cause current varia-- opening the calling tions in a circuit including two line conductors thereof, and a series of automatic switch mechanisms operating in succession in response to said current variations and adapted thereby to connect said line'conductors with the corresponding conductors of another line for telephonic communication.

61. In a telephone exchange system, the combination with. aplurality of metallic line circuits free from operative grounds outside of the central ofiice, of means for producing current variations in any one of said circuits, and a plurality of automatic switches-adapted to operate in succession in response to such current variations to connect one of said metallic line circuits with another for telephonic communication.

62. In an automatic telephone. exchange system, the combination of a, calling telephone line, a called telephone line, a series of automaticswitches for extendin connection from the calling line to the ca led line,

a plurality of .line circuits by which said switches are successively controlled, each said line circuit including the two sides of calling line in series, andmeans for'supplying current over the telephone lines to operate said switches, and for talking purposes also.

68. In a telephone exchange system, the combination of a calling telephone line, a called telephone line, a series of automatic switches for extending connection from the calling line to the called line, means for line to release said switches, means for releasing said switches by the opening of said line, and means for supplying current over the telephone lines p and .for. talking to operate said switches, urposes aI'so'.'- 64. "In'a telephone' exchange system, the combination of a subscribe'rs telephone line,

an automatic switch, a Irot'atable calling de-,

vice-adapted by its backward rotation to intermittentlyjclose together the two s des telephone lines,

. means for opening the said switches '.provided with release mechanism responsive to the opening of the calling line to release the-switches either before or after the called subscriber answers, and means for supplying current over the telephone lines to operate said switches, and

for talking purposes also.

66. In a telephone .system, the combination of telephone lines, trunk-lines, automatic self-contained trunk selectors for selecting idle trunk-lines, automatic self-contained connectors for completing connection with the called telephone lines, line circuit for controlling said selectors and connectors,- said line circuits each including the two sides of a calling telephone line in series, and means for supplying current over the telephone lines-to operate said selectors and connectors, and for talking purposes also.

67. In a telephone system, the combination of a plurality of switches, each-adapted for both primary and secondary motion,v line circuits for successively controlling the said switches to extend connection from a calling'line to a called line,

said line circuits each. including the two sides of the calling line in series, and means for supplying current over the telephone lines, to operate said switches, and for talking purposes also.

68. In a telephone system, the combination of a plurality of automatic switches,-

telephone lines, line circuits for successively controlling said switches to extend connection from a calling line: to a called line,

' the lines when the subscribers hang up rectly responsive'to the opening of a con-u nected telephone line for initiating the release of all switches between the linesof calling and called subscribers, and meansfor supplying current over the telephonelmes to operate said switches, and fortalking puroses also. a

69. In a telephone system, tion of a plurality of :switches, lines, line circuits for ling said switches; to extend connection from a calling line to a called line, sald circults each including the two sidesof a calling telephone line in series, a subscnbers .releasmg successively control- .sides of a calling telephone line in series,

each switch provided with a switch shaft adapted for both primary and secondary motlon, means carried by the shaft of each switch for extending connection in the direction of the called subscriber, and means for supplying current over the telephone lines to operate said switches, and for talking purposes also.

71. In an automatic common battery telephone system, the combination of a calling line and a called line, a series of switches for trunking'thecalling line into connection with the called line, means whereby the calling subscriber may break the connection and restore said switches by simply separating his line conductors, and means .for supplying operating and talking current from the central station, substantially as set forth.

72. In a telephone system, the combina tion of a calling line and a called line, a series of switches for trunking the" calling line into connection with the called line, means whereby the calling subscriber may release the switches, either before or after the called. subscriber answers, by simply opening up his line, and means for supplying operating andv talking current from the central station, substantially as set forth.

73. In a telephone system, the combination of a series of automatic switches, a talking circuit, means for successivel operating said switches, and then releasing the same by controlling circuits including both sides of the talking circuit in series and means for sup lying operating and talking current from t e central station.

74. In a telephone system, a called line,

a connector provided with an element having motion in one direction to select groups and in another direction to find the called line, release mechanism for restoring the connector to normal position, and a single line relay operative to control the motions of said element in both directions and the release of said connector.

75. In. a telephone system, a plurality of trunks, an automatic trunking switch provided with an element having primary and secondary motion to find an idle trunk, and a single line relay operative to control the primary motion and start the secondary motion.

76. In a telephone system, a plurality of trunks, an automatic trunking switch provided with line wipers having primary and secondary motion to find an idle trunk, and a single line relay operative to control the primary motion and start the secondary motion.

77. In a telephone system, a plurality of groups of lines including a called line, a connector provided with line wipers having primary and secondar motion to find the groups and the calle line of groups, and a single line relay operative to control the primary and secondary motion.

78. In a telephone system, the combina tion with groups of lines including a called line, a connector provided with an element having primary and secondary motion to find the group and then the called line of the group, release mechanism for restoring the connector to normal position, a single line relay operative to control the primary and secondary motion and the release of said connector, and means for controlling said relay over a metallic line circuit.

79. In a telephone system, the combination of a plurality of trunks, an automatic trunking switch provided with an element having primary and secondary motion to find an idle trunk, a single line relay operative to control the primary motion and start the secondary motion, and means for controlling said relay over a metallic Kline circuit.

-80. In a telephone system, the combination of a plurality of trunks, an automatic trunking switch provided with line wipers having primary and secondary motion to find an idle trunk, a single line relay opera tive to control the primary motion and start the secondary motion, and means for controlling said' relay over a metallic line circuit.

81. In a telephone system, the combination with a group of lines including a called line, a connector provided .with line wipers having primary and secondary motion to find the group containing the called line and then the called line in the group, a single line relay operative to control the rimary and secondary motion, and means or controlling. said 'relay over a metallic line circuit.

82. An automatic telephone system including calling and called lines, first selectors, second selectors, connectors, means for adjusting said first selectors by impulses over the metallic circuit conductors of the calling'line in series, and means for adjusting the selected second selectors and connectors by re eating the calling line ha pulses at the st selectors.

83. In a telephone exchange system the combination of subscribers telephone lines,

automatic means for extending connection from a calling telephone line to a called telephone line including a wiper having primary and secondary motion, disconnecting or releasing means adapted to be operated by the opening of a telephone line, and

means by which a subscriber when through talking opens his line to therebyoperate the said disconnecting or releasing means without grounding the line.

In testimony whereof I have aflixed my signature.

EDWARD E. CLEMENT. 

